Oxidation of hydrocarbons



jzqdracarbom and/416019011,

Sept. 24} 1940. w. KING ET AL 2,215,474

' OXIDATION OF HYDRQCARBQN;

Origin'al Filed April 2. 193a I 5 w ke/ wafer de/z'ga'er azzdAcidrWillazzz fiz/f 122g v 1 Cl 6 266 y INVENTORS g BY ATTORNEY PatentedSept. 24, 1940 UNITED STATES OXIDATION OF HYDROCARBONS I William 11.King, New Orleans, La., and Clyde Q. Sheely, State College, Miss.

Original application April 2, 1938, Serial No. 199,636. Divided and thisapplication July 26,

1939, Serial No. 286,616

, 1 Claim.

This invention relates to a new and improved process for the preparationof chemical compounds by the oxidation of aliphatic hydrocarbons in thepresence of a catalyst, and more particu- 5 larly to such a processwherein the reaction products comprise aliphatic alcohols, aldehydes andacids.

This application is a continuation-in-part of our copending applicationSerial No. 108,478, filed October 30, 1936, and is a division of ourcopending application Serial No. 199,636, filed April 2, 1938.

The higher aldehydes of the aliphatic series have considerable value aschemical compounds and a number of them have found use in industry 16 asperfumes. The difiiculties in the way of preparing such compounds,however, have kept their costs so high as to limit their field ofusefulness. An improved and simpler method of obtaining such aldehydeswould make more accessible a very m desirable class of products. Thesame condition holds in the case of a number of the higher aliphaticalcohols and acids also, for example those containing in theneighborhood of 8 to 12 carbon atoms.

25 An object of our invention is an improved method for the productionof alcohols, aldehydes, and acids by the incomplete oxidation ofaliphatic hydrocarbons. A further object is such a process in whichcarefully controlled conditions allow a 30 high degree of efiiciency inthe preparation of .the

desired products. A still further object is a process in which theseveral products obtained may be separated in relatively pure form.Additional objects will be disclosed as the process is further 35described hereinafter.

We have found that the foregoing objects may be accomplished by theprocess of our invention which comprises introducing a normally liquidhydrocarbon in the vapor phase into a heated o chamber, together with anoxidizing agent comprising a gas containing free oxygen. The oxida tionstep is carried out in the presence of nitrobenzene as a catalyst.Withinthe reaction chamber the mixed gases and vapors are subjected to 5a temperature between 250 and 500 C. while the oxidation of thehydrocarbons constitutes an exothermic reaction, the heat evolved willnot be sumcient to maintain the desired temperature and external heatingwill be necessary. It is essential 60 that the reaction period be keptat a relatively short time interval, and we have found '15 seconds to bethe maximum allowable time. Preferably we employ a reaction periodnotgreater than 12 seconds, in orderthat the oxidation may not pro- 55 ceedtoo far. The reacting materials and reaction products are removed fromthe heated chamber while still in the vapor phase and are condensed byany desired method and apparatus under such conditions and in such anatmosphere that further reaction cannot take place. The amount ofhydrocarbon will be above the explosive limit in all cases. W have foundit desirable to use an amount of hydrocarbon 'of at least 10% by volumeof the gaseous reaction mixture, and preferably between 20 and 40%. 10It will be a desirable step in our process also to utilize the unreactedhydrocarbon resulting from the process and to recycle it to anadditional similar oxidation step, whereby the advantages of thepresence of an excess of hydrocarbon are obtained 15 with no loss innon-reacting material.

The accompanying drawing shows diagrammatically a flow sheet of onemethod of carrying out our process. From a reservoir l, the normallyliquid hydrocarbon is forced through conduit 2 into the preheater 3. Thegas containing free oxygen is passed through conduit 4 through thepreheater 3, en route to the reaction chamber 5. Both the vaporizedhydrocarbon and the oxygen containing gas pass into the reaction chamber5 where they become intimately mixed and where a temperature of 250 to500 C. is maintained, .said catalyst, promoting partial oxidation, beingpresent, whereby partial oxidation of the hydrocarbons is brought about.The vapors pass out the conduit 6 into separator I, where any tar formedin the process is separated out. The mixed vapors and gases then passthrough con-. denser 8, where the products capable of condensationbecome liquefied. The liquid condensate flows into reservoir 9, while asecond vessel l0 receives any further condensed product not caught inchamber 9, but condensed in -l I. The reservoirs 9 and I0 contain theliquefied unreacted hydrocarbon that has passed through the process, and0 also condensed water and the alcohols, aldehydes and acids resultingfrom the oxidation process. Such alcohols, aldehydes and acids willcommonly be found in the water-insoluble layer.

Specific operating conditions suitable for our process for theproduction of alcohols, aldehydes, and acids are shown in the followingexample. This is to be considered as merely illustrative, however, andnot limiting in its application Example 5 cc. of nitrobenzene wasdissolved in 200 cc. of naphtha. This mixture was vaporized in the usualmanner and mixed with 'air at a temperature of 387 C. The timecofreaction was 5.255

seconds and the percentage of hydrocarbon in the reaction mixture was18.7. The yield w 16.84% aldehydes and 14.15% acids.

The method of operation according to the present invention producesalcohols. aldehydes and acids. However, it isespecially favorable to theproduction of alcohols.

The alcohols, aldehydes and acids resulting from the oxidation ofhydrocarbons according to the process of our invention, are products ofconsiderable economic value and of desirable properties, and the processdescribed offers a novel and advantageous method of obtaining suchproducts. Our process is characterized by higher yields and greatereiliciency than any process in the art.

The alcohols, aldehydes and acids may be separated from the hydrocarboncondensate and from one another by the use of suitable solvents. In

the case of aldehydes, for example, a saturated solution of sodiumbisulfite was found desirable for extraction, the bisulfite subsequentlybeing made alkaline and being subjected to steam distillation. The acidswere desirably extracted by means of sodium hydroxide solution. Thealcohols are preferably extracted by means of phosphoric' acid.

While our process has been described in detail in the foregoing, it willbe understood that many variations in procedure may be employed withoutdeparting from the scope of our invention. In the example cited, ahydrocarbon fraction of a specific distillation range was used, but itwould be a highly desirable procedure also to.start with asinglealiphatic hydrocarbon, ior example octane, or a mixture ofoctanes.

We wish to be limited, therefore, only by the following patent claim.

.We claim:

'The process for producing partially oxidized products of normallyliquid aliphatic hydrocarbons which comprises introducing saidhydrocarbons in vapor phase, together with an oxidizing agent comprisinga gas containing free oxygen, into a reaction chamber at a temperaturebetwen 250 C. and 500 C., and reacting said materials for a period notexceeding 15 seconds in the presence of nitrobenzene.

WILLIAM H. KING. CLYDE Q. SHEELY.

